Abstract: A d.c. or a.c. electroluminescent panel comprises a transparent substrate, a transparent first electrode film, a thin film phosphor layer, a black or dark powder back layer of electrically conductive material, and a second electrode film. Application of a voltage across the phosphor layer causes it to emit light. In this invention, the black powder back-layer significantly enhances the contrast of the panel.

Abstract: The present invention concerns an electroluminescent panel suitable for unidirectional and/alternating voltage order, a transparent glass substrate (10), a thin transparent front electrode film (12) made of indium-tin-oxide, a first thin (preferably 1-2 microns thick) layer (14) of a phosphor in the form of powder particles, the surface of the particles being free of any metallic coating, e.g. Cu coating, an electrically conducting, dark powder layer (16) which is a control layer consisting e.g. of MnO.sub.2 uncoated or undoped with Cu and a (preferably aluminium) back electrode layer )18).

Abstract: A d.c. or a.c. electroluminescent panel comprises a transparent substrate, a transparent first electrode film, a thin film phosphor layer, a control layer and a second electrode film. A black or dark colored material, less than 1 micron thick, is interposed between the thin film phosphor layer and the control layer to enhance the contrast of the panel whenever a voltage is applied across the thin film phosphor layer causing it to emit light.

Abstract: A display device includes a layer of electroluminescent material which is capable of conducting electric current. The electroluminescent material is sandwiched between a pair of electrodes to which a voltage is to be applied to excite the electroluminescent material to luminescence. The display device is manufactured by disposing on an assembly comprising a substrate with one of the said electrodes thereon, two masks in which are formed aligned apertures defining a region in which the electroluminescent material is to be provided. The electroluminescent material is disposed in the apertures, and, after that material has solidified one of the masks is removed, the other of the electrodes then being formed on the exposed surface of the electroluminescent material and within slots in the remaining mask and the mask is removed.